German patent application No. 34 38 209 discloses a disc brake of this type. The actuating shaft is cylindrically and rotatably mounted in a slide bearing, and a shaft sealing ring is placed in the area of a shaft duct which has a sealing lip that abuts on the periphery of the actuating shaft.
The manufacture of disc brakes of this type necessitates great effort and structure because the actuating shaft necessitates the provision of a cylindrical abutment surface in the area of the shaft sealing ring, on the one hand. On the other hand, a recess must be provided in the area of a pressure member, which is principally carried out by metal-cutting processes. In general, profile bars are meanwhile employed as actuating shafts having a recess which extends over the total overall length of the actuating shaft. This eliminates at least the need to manufacture the recess. However, no satisfactory solution has been found until now for sealing the mounting support of such actuating shafts against the ingress of dirt and moisture from outside. This frequently results in actuating shafts stuck with corrosion and, hence, defective disc brakes.
Therefore, an object of the present invention is to provide a reliable and also inexpensive sealing of the mounting support of profiled actuating shafts which permits reliable functioning over the total useful life of the disc brakes and, in addition, and minimizes losses due to friction.
This object is achieved by the brake system of the present invention wherein, in the area of a shaft duct, a sealing element is provided which is fixed to the actuating shaft so as to rotate along with it and cooperates with associated sealing elements and/or sealing surfaces in a radial direction. Another advantage is achieved because the sealing element that is movable along with the actuating shaft cooperates with an associated supplementary sealing element and/or an associated sealing surface also in an axial direction.
The present invention contemplates the combination of profiled actuating shafts with conventional and customary sealing elements or, respectively, with easy-to-make sealing surfaces. This minimizes the necessary costs.
Costs may be reduced even further by configuring the sealing element as a bushing, which can be manufactured of sheet metal or plastics material by way of deepdrawing processes, for example. A bushing provided as a snap-in element can be fitted to the actuating shaft easily and at low cost.
A functional advantage related to sealings can be achieved by forming a collar to the bushing on the side of the shaft end. Additionally, the collar includes a sealing surface for the axial abutment of a sealing element.
The sealing element has a disc-shaped configuration and includes radially outside and axial sealing lips which serve to abut on mating sealing surfaces. This produces together with axial sealing lips a prechamber in front of the radial seal which additionally improves the sealing effect of the sealing element.
In a preferred aspect of the present invention, the sealing element includes at least one recess into which a carrier element of the actuating lever is engaged. This achieves an improved connection of the sealing element to the shaft for rotation therewith.